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Step 12Tales from the Comments
9 April 2010: I'm adding this step to address some of the comment subjects of the comments...with 384 comments and counting, it's not nearly as easy to just read through them.
1) Dry ice has a lower specific heat capacity than water ice, so while it is colder, it won't last as long.
2) Dry ice sublimates to CO2, which, in a confined space, will at best impair judgment, and at worst cause loss of consciousness. Driving a car requires being alert. I highly discourage using dry ice.
Seems like a good idea, I know--add 12V and that little plate gets frosty cold. But you have to consider the net movement of heat. All that a peltier does is create a heat differential...a difference in temperature between the two sides. It does this by moving the heat from one side to the other. If you put a peltier inside the car, it won't cool anything down, because the same amount of heat that is removed to make one side cool is released on the other side right back into the car. The only way this could possibly work is if it was mounted so that the heat was released outside the car.
Using salt water or alcohol to lower the freezing point, so it will be colder...not really. The temperature is determined by how cold your freezer is. Oh, and salt water is corrosive and will OM NOM NOM your heater core.
Let's take this
Remember the energy flow. If you freeze the ice in your own freezer, all the heat that is pulled out of the ice, and then some, is released into your house from the coils in the back of the freezer. You could use this to cool that hot bedroom, but the house as a whole will be warmed.
Dry ice instead of water ice
First, a clarification: water ice isn't 32°F, it's whatever the temperature of the freezer is, anything below 32degF...just like how the steel on your car can be 10°F on a cold day, or 100°F on a hot day. Dry ice can be any temperature below -109°F. Since it is much colder, id would theoretically put out colder air. The two main problems with this idea are:1) Dry ice has a lower specific heat capacity than water ice, so while it is colder, it won't last as long.
2) Dry ice sublimates to CO2, which, in a confined space, will at best impair judgment, and at worst cause loss of consciousness. Driving a car requires being alert. I highly discourage using dry ice.
Peltier Junctions
Seems like a good idea, I know--add 12V and that little plate gets frosty cold. But you have to consider the net movement of heat. All that a peltier does is create a heat differential...a difference in temperature between the two sides. It does this by moving the heat from one side to the other. If you put a peltier inside the car, it won't cool anything down, because the same amount of heat that is removed to make one side cool is released on the other side right back into the car. The only way this could possibly work is if it was mounted so that the heat was released outside the car.Isn't this just a swamp cooler?
Uhhhhhhhhhh....NO. A swamp cooler works by blowing air over wet stuff (straw, wool, air, you name it), which evaporates the water. Since evaporation is an endothermic process (splash alcohol on your hand and feel how much it cools as it evaporates), the air is cooled down---BUT is also wet and full of all the water that just evaporated, making it only suitable for places that are hot and dry. This air conditioner is simple heat transfer--heat is transferred out of the air into the ice water. Since the ice water is cold, vapor in the air condenses on the coils, so it actually pulls water out...making it much more suitable for humid Kansas summers.
Ye salty sea dog!
Using salt water or alcohol to lower the freezing point, so it will be colder...not really. The temperature is determined by how cold your freezer is. Oh, and salt water is corrosive and will OM NOM NOM your heater core.Liquid Nitrogen
Er...for the same cost, you could buy a new car...which has air conditioning...and doesn't involve frostbite...Let's take this Outinside
Remember the energy flow. If you freeze the ice in your own freezer, all the heat that is pulled out of the ice, and then some, is released into your house from the coils in the back of the freezer. You could use this to cool that hot bedroom, but the house as a whole will be warmed.OH NOEZ T3H POLAR BEARS
Yeah, yeah, it takes energy to freeze water, yada yada yada. If you can't handle your freezer running a bit extra, then quit whining and roll down the window.Using the existing core
Yes, you can hook it up to run cold water through the original heater core so it blows through the original ducts. The whole point of this was to be portable, though. If you want a more permanent installation, have at it.| « Previous Step | Download PDFView All Steps | Next Step » |
This is a really great Instructable! It really got my creative juices flowing, thank you so much for that!
In the teardrop, if you are camping next to a stream, you can use two long hoses and a funnel to catch the water flow, divert it to the Teardrop where the pump can take over and pump it up into the teardrop. The teardrop is cooled and then the water is returned to the stream! Call it a "Gone Green A/C Cooler!" Hey, come to think of it, that would supply the Teardrop with a source of water that could quickly be purified using a ceramic filter for consumption!
I am curious though, how much longer would the cooling effect last if the lid were closed?
Let's say you mount the heater core outside of the cooler, leaving the lid intact except for hoses in and out (via split rear window, perhaps?). This way the ambient air isn't being pulled over the ice and melting it faster.
With this in mind, you could potentially put the cooler in the truck bed, and add an inline peltier device to cool the water in the return line, exchanging the heat with the great outdoors and helping your icebox to last longer...and making more legroom for your passenger!
(no need to plug into 12v power than!
Apologies for the poorly worded statement, I'll try to make it more clear.